Download Elenco Electronics LP-525K Instruction manual

LOGIC PROBE KIT
MODEL LP-525K
Assembly and Instruction Manual
ELENCO
®
Copyright © 2013, 1994 by Elenco® Electronics, Inc. All rights reserved.
Revised 2013
REV-J
No part of this book shall be reproduced by any means; electronic, photocopying, or otherwise without written permission from the publisher.
753241
PARTS LIST
If you are a student, and any parts are missing or damaged, please see instructor or bookstore.
If you purchased this LP-525K Logic Probe Kit from a distributor, catalog, etc., please contact ELENCO®
(address/phone/e-mail is at the back of this manual) for additional assistance, if needed. DO NOT contact your
place of purchase as they will not be able to help you.
RESISTORS
Qty.
r 3
r 1
r 1
r 1
r 1
r 1
r 2
r 2
r 7
r 1
r 1
r 3
Symbol
R21, R23, R24
R16
R4
R14
R11
R13
R10, R15
R12, R22
R1, R5 - R8, R19, R20
R17
R18
R2, R3, R9
Description
200Ω 5% 1/4W
2kΩ 5% 1/4W
4.7kΩ 5% 1/4W
5.1kΩ 5% 1/4W
15kΩ 5% 1/4W
18kΩ 5% 1/4W
20kΩ 5% 1/4W
30kΩ 5% 1/4W
100kΩ 5% 1/4W
120kΩ 5% 1/4W
150kΩ 5% 1/4W
4.7MΩ 5% 1/4W
Color Code
red-black-brown-gold
red-black-red-gold
yellow-violet-red-gold
green-brown-red-gold
brown-green-orange-gold
brown-gray-orange-gold
red-black-orange-gold
orange-black-orange-gold
brown-black-yellow-gold
brown-red-yellow-gold
brown-green-yellow-gold
yellow-violet-green-gold
Part #
132000
142000
144700
145100
151500
151800
152000
153000
161000
161200
161500
174700
CAPACITORS
Qty.
r 1
r 1
r 2
Symbol
C2
C3
C1, C6
Description
100pF (101) Discap
200pF (201) Discap
0.001µF (102) Discap
Part #
221017
222010
231036
Qty.
r 1
r 1
r 1
Symbol
C4
C5
C7
Description
0.005µF (502) Discap
0.047µF (473) Discap
0.1µF (104) Discap
Part #
235018
244780
251010
Description
2N3906 Transistor
LM2901 IC
LED
Part #
323906
332901
350001
SEMICONDUCTORS
Qty.
r 1
r 5
r 2
Symbol
D6
D1 - D5
Q2, Q4
Description
1N4002 Diode
1N4148 Diode
2N3904 Transistor
Qty.
r 1
r 2
r 1
r 1
r 2
r 1
r 1
Description
PC board
Switch SPDT
Probe tip
Case
Screw #4 x 5/8”
IC socket 14-pin
Label front
Part #
314002
314148
323904
Qty.
r 3
r 1
r 3
Symbol
Q1, 3, 5
U1
L1 - L3
MISCELLANEOUS
Part #
517014
541024
616001
623005
643450
664014
724002
Qty.
r 1
r 1
r 1
r 3”
r 1”
r 1
Description
Label back
Wire 1.5”
Power cord
Tubing #20
Shrink tubing (red)
Solder tube lead-free
Part #
724003
814220
862102
890020
890312
9LF99
PARTS IDENTIFICATION
Resistor
Diode
Integrated Circuit
Capacitor
Transistor
IC Socket
LED
Switch
-1-
Case Top
Probe Tip
Case Bottom
Power Cord
IDENTIFYING RESISTOR VALUES
Use the following information as a guide in properly identifying the value of resistors.
BAND 1
1st Digit
Color
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Gray
White
BAND 2
2nd Digit
Digit
0
1
2
3
4
5
6
7
8
9
Color
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Gray
White
Multiplier
Digit
0
1
2
3
4
5
6
7
8
9
Color
Black
Brown
Red
Orange
Yellow
Green
Blue
Silver
Gold
Resistance
Tolerance
Multiplier
1
10
100
1,000
10,000
100,000
1,000,000
0.01
0.1
Color
Silver
Gold
Brown
Red
Orange
Green
Blue
Violet
Tolerance
±10%
±5%
±1%
±2%
±3%
±0.5%
±0.25%
±0.1%
BANDS
2
1
Multiplier
Tolerance
IDENTIFYING CAPACITOR VALUES
Capacitors will be identified by their capacitance value in pF (picofarads), nF (nanofarads), or µF (microfarads).
Most capacitors will have their actual value printed on them. Some capacitors may have their value printed in
the following manner. The maximum operating voltage may also be printed on the capacitor.
(–)
0
1
2
3
Multiply By
1
10
100
1k
CERAMIC DISC
Second digit
4
5
8
10k 100k .01
Multiplier
First digit
50V
Second digit
Tolerance*
Maximum working voltage
Polarity
marking
(–)
(may or may not appear
on the cap)
Radial
The value is 22 x 100 =
2,200pF or .0022µF, +5%, 100V
The value is 10 x 10 =
100pF, +10%, 50V
* The letter M indicates a tolerance of +20%
(+)
Axial
The letter K indicates a tolerance of +10%
The letter J indicates a tolerance of +5%
Note: The letter “R” may be used at times
to signify a decimal point; as in 3R3 = 3.3
METRIC UNITS AND CONVERSIONS
Abbreviation
p
n
µ
m
–
k
M
0.1
Tolerance*
Multiplier
101K
9
MYLAR
First digit
If the capacitor is
connected with
incorrect polarity, it
may heat up and
either leak, or
cause the capacitor
to explode.
(+)
For the No.
100V
Warning:
Multiplier
2A222J
Electrolytic capacitors have a positive
and a negative electrode. The
negative lead is indicated on the
packaging by a stripe with minus
signs and possibly arrowheads. Also,
the negative lead of a radial
electrolytic is shorter than the positive
one.
Means
Pico
nano
micro
milli
unit
kilo
mega
Multiply Unit By
.000000000001
.000000001
.000001
.001
1
1,000
1,000,000
Or
10-12
10-9
10-6
10-3
100
103
106
-2-
1. 1,000 pico units
= 1 nano unit
2. 1,000 nano units
= 1 micro unit
3. 1,000 micro units = 1 milli unit
4. 1,000 milli units
= 1 unit
5. 1,000 units
= 1 kilo unit
6. 1,000 kilo units
= 1 mega unit
CIRCUIT DESCRIPTION
The Elenco® Model LP-525K Logic Probe kit is a
convenient and precise instrument for use in the
measurement of logic circuits. It displays logic
levels (high or low), and voltage transients down to
25 nanoseconds. The LED readouts provide instant
response to the logic state.
becomes more negative than the (+) input and the
comparator turns off. The short pulse on the input is
thus stretched to 1.5 milliseconds.
The (–) input (pin 8) of the PULSE LED driver is
biased to +2.5VDC by resistors R19 and R20. The
(+) input is biased to +3VDC by resistors R6 and
R18. The 1.5 milliseconds pulse from the pulse
stretcher grounds the (+) input through diode D5
turning the comparator on and lighting the PULSE
LED. When the PULSE-MEM switch is in MEM, Q5
is also turned on, causing the (–) input of the
comparator to go to +5VDC. This keeps the
comparator on even after the (+) input returns to
+3VDC. When the PULSE-MEM switch is in
PULSE, the feedback path to the (–) input is broken
and the LED is lit only for the duration of the 1.5
milliseconds pulse.
To detect the high and low logic levels, the LP-525
uses two comparators of a Quad Comparator
LM2901 Integrated Circuit (see schematic diagram).
One comparator drives the HI LED and the other
drives the LOW LED. The comparator output goes
low, lighting the LED, when the (–) input is more
positive than the (+) input. To measure TTL circuits,
the TTL-CMOS switch is set to TTL and the red and
black alligator clips are connected to +5VDC and
ground. The (+) input (pin 5) of the HI comparator is
then biased to 2.3VDC by resistor network R9
through R15. Thus, the LED lights when the probe
tip is more positive than 2.3VDC. To measure
CMOS circuits, the HI comparator changes to
3.5VDC or 70% of the supply voltage.
Thus, each time the input signal changes state, the
PULSE LED is activated for 1.5 milliseconds. When
observing low frequency signals, the PULSE LED
provides an immediate indication of this pulse
activity. By observing the HI and LOW LEDs, the
polarity of the pulse train can be determined. Low
frequencies cause the PULSE LED to blink once for
each transition. High frequencies cause the LED to
flash at a rate that makes it appear to be on
continuously. When the PULSE-MEM switch is in
MEM, a single input pulse will cause the PULSE
LED to come on and stay on until the switch is
returned to the PULSE position.
The (–) input of the LOW comparator is biased to
0.8VDC for TTL operation and 1.5VDC or 30% of
the supply voltage for CMOS operation. The LOW
LED thus lights when the probe tip is connected to
voltages less than 0.8 or 1.5VDC.
The pulse LED is controlled by a bipolar edge
detector circuit which responds to both positive and
negative transients. This circuit is made up of
capacitors C2 and C3, transistors Q1 through Q4,
and the associated resistors. When the circuit is
activated by pulses as short as 25 nanoseconds, a
negative pulse is applied to the (+) input (pin 11) of
the pulse stretcher comparator. The comparator
then turns on and is held by the feedback resistor
R8. The ground level on the output (pin 13) causes
C5 to discharge through R17. In approximately 1.5
milliseconds, the voltage on the (–) input (pin 10)
The input impedance of the LP-525 is 1MΩ. This
eliminates any loading effect on the circuit under
test.
CAUTION: Do not connect the alligator clips to any
AC power source or to a DC power source greater
than 35VDC. Failure to comply with this warning
may result in damage to this instrument.
SPECIFICATIONS
Input Impedance
Input Overload Protection
Thresholds
TTL
CMOS
Response better than
Pulse Detector
Power Requirements
Operating Temperature
1MΩ
35V DC continuous
Logic 1
Logic 0
2.3 + .25V
0.80V + .1V
70% Vcc
30% Vcc
25 nanoseconds
1.5 millisecond pulse stretcher
5V Vcc @ 30mA
15V Vcc @ 40mA
0OC to +40OC
-3-
CONSTRUCTION
Introduction
• Turn off iron when not in use or reduce temperature setting when
using a soldering station.
The most important factor in assembling your LP-525K Logic Probe Kit
is good soldering techniques. Using the proper soldering iron is of prime
importance. A small pencil type soldering iron of 25 watts is
recommended. The tip of the iron must be kept clean at all times
and well-tinned.
• Tips should be cleaned frequently to remove oxidation before it becomes
impossible to remove. Use Dry Tip Cleaner (Elenco® #SH-1025) or Tip
Cleaner (Elenco® #TTC1). If you use a sponge to clean your tip, then use
distilled water (tap water has impurities that accelerate corrosion).
Solder
Safety Procedures
For many years leaded solder was the most common type of solder
used by the electronics industry, but it is now being replaced by leadfree solder for health reasons. This kit contains lead-free solder, which
contains 99.3% tin, 0.7% copper, and has a rosin-flux core.
• Always wear safety glasses or safety goggles to
protect your eyes when working with tools or
soldering iron, and during all phases of testing.
• Be sure there is adequate ventilation when soldering.
Lead-free solder is different from lead solder: It has a higher melting
point than lead solder, so you need higher temperature for the solder to
flow properly. Recommended tip temperature is approximately 700OF;
higher temperatures improve solder flow but accelerate tip decay. An
increase in soldering time may be required to achieve good results.
Soldering iron tips wear out faster since lead-free solders are more
corrosive and the higher soldering temperatures accelerate corrosion,
so proper tip care is important. The solder joint finish will look slightly
duller with lead-free solders.
• Locate soldering iron in an area where you do not have to go around
it or reach over it. Keep it in a safe area away from the reach of
children.
• Do not hold solder in your mouth. Solder is a toxic substance.
Wash hands thoroughly after handling solder.
Assemble Components
In all of the following assembly steps, the components must be installed
on the top side of the PC board unless otherwise indicated. The top
legend shows where each component goes. The leads pass through the
corresponding holes in the board and are soldered on the foil side.
Use only rosin core solder.
Use these procedures to increase the life of your soldering iron tip when
using lead-free solder:
• Keep the iron tinned at all times.
• Use the correct tip size for best heat transfer. The conical tip is the
most commonly used.
DO NOT USE ACID CORE SOLDER!
What Good Soldering Looks Like
Types of Poor Soldering Connections
A good solder connection should be bright, shiny, smooth, and uniformly
flowed over all surfaces.
Soldering Iron
1. Solder all components from the
copper foil side only. Push the
soldering iron tip against both the
lead and the circuit board foil.
Rosin
Component Lead
1. Insufficient heat - the solder will
not flow onto the lead as shown.
Foil
Soldering iron positioned
incorrectly.
Circuit Board
2. Apply a small amount of solder to
the iron tip. This allows the heat
to leave the iron and onto the foil.
Immediately apply solder to the
opposite side of the connection,
away from the iron. Allow the
heated component and the circuit
foil to melt the solder.
3. Allow the solder to flow around
the connection. Then, remove
the solder and the iron and let the
connection cool. The solder
should have flowed smoothly and
not lump around the wire lead.
Soldering Iron
2. Insufficient solder - let the
solder flow over the connection
until it is covered.
Use just enough solder to cover
the connection.
Solder
Foil
Solder
Gap
Component Lead
Solder
3. Excessive solder - could make
connections that you did not
intend to between adjacent foil
areas or terminals.
Soldering Iron
Solder
Foil
4. Solder bridges - occur when
solder runs between circuit paths
and creates a short circuit. This is
usually caused by using too
much solder.
To correct this, simply drag your
soldering iron across the solder
bridge as shown.
4. Here is what a good solder
connection looks like.
-4-
Soldering Iron
Foil
Drag
ASSEMBLE COMPONENTS TO THE PC BOARD
Refer to the top legend on the PC board, install and solder the following resistors.
Stand resistor on end
when called for.
Figure 1
R23 - 200Ω Resistor
(red-black-brown-gold)
(see Figure 1)
R13 - 18kΩ Resistor
(brown-gray-orange-gold)
R1 - 100kΩ Resistor
(brown-black-yellow-gold)
R9 - 4.7MΩ Resistor
(yellow-violet-green-gold)
R24 - 200Ω Resistor
(red-black-brown-gold)
R10 - 20kΩ Resistor
(red-black-orange-gold)
R14 - 5.1kΩ Resistor
(green-brown-red-gold)
R12 - 30kΩ Resistor
(orange-black-orange-gold)
R11 - 15kΩ Resistor
(brown-green-orange-gold)
R20 - 100kΩ Resistor
(brown-black-yellow-gold)
(see Figure 1)
R8 - 100kΩ Resistor
(brown-black-yellow-gold)
R6 - 100kΩ Resistor
(brown-black-yellow-gold)
R17 - 120kΩ Resistor
(brown-red-yellow-gold)
(see Figure 1)
R19 - 100kΩ Resistor
(brown-black-yellow-gold)
R7 - 100kΩ Resistor
(brown-black-yellow-gold)
(see Figure 1)
R2 - 4.7MΩ Resistor
(yellow-violet-green-gold)
R22 - 30kΩ Resistor
(orange-black-orange-gold)
R15 - 20kΩ Resistor
(red-black-orange-gold)
R21- 200Ω Resistor
(red-black-brown-gold)
R16 - 2kΩ Resistor
(red-black-red-gold)
R3 - 4.7MΩ Resistor
(yellow-violet-green-gold)
R5 - 100kΩ Resistor
(brown-black-yellow-gold)
(see Figure 1)
Save 5 discarded leads for jumper wires.
-5-
R4 - 4.7kΩ Resistor
(yellow-violet-red-gold)
ASSEMBLE COMPONENTS TO THE PC BOARD
Refer to the top legend on the PC board, install and solder the following diodes, capacitors and jumper wires.
When mounting diodes
vertically, mount as
indicated by band.
(Diodes have polarity).
Figure 2
Form jumper wire from discarded
resistor lead.
Figure 3
When mounting diodes horizontally,
mount as indicated by the band.
(Diodes have polarity).
Figure 4
D1 - 1N4148 Diode
(see Figure 2)
D2 - 1N4148 Diode
(see Figure 2)
C1 - .001µF Capacitor
(May be marked 102)
J - Jumper Wire
(see Figure 3)
J - Jumper Wire
(see Figure 3)
J - Jumper Wire
(see Figure 3)
D5 - 1N4148 Diode
(see Figure 4)
C2 - 100pF Capacitor
(May be marked 101)
J - Jumper Wire
(see Figure 3)
C5 - .047µF Capacitor
(May marked 473)
J - Jumper Wire
(see Figure 3)
C6 - .001µF Capacitor
(May be marked 102)
D6 - 1N4002 Diode
(see Figure 4)
C3 - 200pF Capacitor
(May be marked 201)
C4 - .005µF Capacitor
(May be marked 502)
D3 - 1N4148 Diode
(see Figure 4)
C7 - .1µF Capacitor
(May be marked 104)
D4 - 1N4148 Diode
(see Figure 4)
-6-
ASSEMBLE COMPONENTS TO THE PC BOARD
Refer to the top legend on the PC board, install and solder the following components.
Insert the IC socket
into the PC board
with the notch in the
direction shown on
the
top
legend.
Solder the IC socket
into place. Insert the
IC into the socket
with the notch in the
same direction as the
notch on the socket.
Mount the transistor with the flat side in the
direction shown on the top legend. Leave
1/4” between the part and PC board.
IC
Flat
Side
Flat Side Marking
Figure 7
Socket
PC Board
Figure 5
Cut a 3/8” piece of tubing for each
LED lead, to be used as stand-offs.
Mount the LED with the flat side in
the direction shown on the top
legend.
Before installing, snip off the tabs. Mount the
switch so that the legs are touching the PC
board.
Flat
Side
Tubing
Figure 8
3/8”
Flat Side
Marking
} Leg
Tab
{
Cut off tabs
Figure 6
L1 - LED
(see Figure 8)
U1 - 14-pin IC Socket
U1 - LM2901 IC
(see Figure 5)
L2 - LED
(see Figure 8)
SW1 - Switch
(see Figure 6)
L3 - LED
(see Figure 8)
Q2 - 2N3904 Transistor
(see Figure 7)
R18 - 150kΩ Resistor
(brown-green-yellow-gold)
Install SW1 first.
Q1 - 2N3906 Transistor
(see Figure 7)
SW2 - Switch
(see Figure 6)
Q5 - 2N3906 Transistor
(see Figure 7)
Q4 - 2N3904 Transistor
(see Figure 7)
Q3 - 2N3906 Transistor
(see Figure 7)
-7-
r Install the power cord as shown in Figure 9. Solder the red wire to hole
marked “+” and the green wire to the hole marked “–” (see Figure 9).
r Install the probe tip as shown in Figure 10. Using the 1 1/2” wire, strip 1/4”
of insulation off of both ends. Solder one end to point P on the PC board.
Solder the other end of the wire to the probe tip groove.
Red wire
(to + hole)
Green wire
(to – hole)
r Install the two labels to the case, as shown in Figure 11. Be careful to place
the labels on neatly and correctly. Peel the backing off to expose the glue.
r Place the PC board assembly into the case as shown in Figure 11. Use two
#4 screws to hold the case together. Do not over-tighten or the holes may
strip out.
Figure 9
r Cut a 13/16” piece of red shrink tubing and slide it over the probe tip until
it touches the plastic case. Shrink the tubing by heating it with your
soldering iron. Be sure the soldering iron does not contact the tubing or
plastic case.
This completes the assembly procedure. Your Logic Probe is now ready for
testing.
Figure 10
Top label
Top case
Red shrink tubing
Assembled
PC board
Bottom case
#4 x 5/8” Screw
Bottom label
#4 x 5/8” Screw
Figure 11
-8-
CAUTION:
Do not connect the alligator clips to any AC power source or to DC power source greater than
35VDC. Failure to comply to this warning may result in damage to this instrument.
TESTING YOUR DIGITAL PROBE
Checking out your Logic Probe for proper operation is
fairly easy. All that is needed is a 9V battery or other DC
power source (5-10V). Connect the red alligator clip to
the positive terminal of the battery and the black clip to
the negative terminal. Set the PULSE-MEM switch to the
PULSE position and the TTL-CMOS switch to the TTL
position. Touch the probe tip to the positive side of the
battery, the PULSE LED should blink once and the HIGH
LED should light up. Place the probe tip to the negative
terminal and the LOW LED should light up. To check the
operation of the memory switch, set the PULSE-MEM
switch to the MEM position and set the TTL-CMOS
switch to the TTL position. Now touch the probe tip to the
positive side of the battery. The PULSE LED should
come on and stay on until the switch is flipped back to the
pulse position. No LED’s should light up when the tip is
not touching anything (open circuit).
The logic probe should operate at the following logic
levels when the power supply voltage is precisely set to
5VDC.
DTL/TTL Position
Logic 0 - under 0.8V + 0.1V
Logic 1 - above 2.3V + 0.25V
CMOS Position
Logic 0 - under 1.5V + 0.2V
Logic 1 - above 3.5V + 0.35V
TROUBLESHOOTING CHART
Condition
Possible Cause
No LED’s light up.
Power cord
Check U1, C7, or D6.
HIGH LED or LOW LED never lights.
Check U1.
Test LED by shorting pins 1, 2, or 14 to negative supply.
HIGH or LOW LED always on.
Pulse LED always on.
PULSE LED never flashes.
All LED’s flash.
Check U1, R9 to R15.
Check Q3 - Q5, U1.
Check LED 3, Q1 - Q4, D3, D4.
Noise on power line.
FOIL SIDE OF PC BOARD
-9-
OPERATING INSTRUCTIONS
To operate the logic probe, connect the two alligator clips to the circuit DC
power supply, red clip to the positive voltage, black to ground. BE SURE
THE CIRCUIT SUPPLY IS UNDER 35V OR DAMAGE MAY OCCUR TO
THE PROBE. Set the logic family switch to TTL or CMOS. Touch the
probe tip to the circuit node to be analyzed. The LED display on the probe
body will light to indicate the condition of the node. Refer to the chart
below to interpret the LED readings. To prevent power supply spikes,
connect the leads as close to the node to be tested as possible.
LED STATES
HIGH
LO
PULSE
INPUT
SIGNAL
Logic “0” no pulse activity.
Interpreting
the LEDs
Logic “1” no pulse activity.
All LEDs off
1. Test point is an open circuit.
2. Out of tolerance signal.
3. Probe not connected to power.
4. Node or circuit not powered.
LED On
LED Off
*
LED Blinking
*
Equal brightness of the HI and LO LED indicates
approximately a 50% duty cycle square wave.
*
High frequency square wave greater than
approximately 3MHz.
Logic “0” with positive pulses present. Low duty
cycle since HI LED is not on. If duty cycle were
increased, the HI LED would start to turn on.
Logic “1” with negative pulses present. High duty
cycle since LO LED is not on. If duty cycle were
reduced, the LO LED would start to turn on.
*
*
GLOSSARY
Alternating Current (AC)
Non-polarized power that is
constantly changing back and
forth between positive and
negative.
Light Emitting Diode (LED)
A semiconductor device that
glows when power is applied to
its electrodes.
Anode
The positive terminal of a diode
or other polarized component.
Logic Probe
An electronic test device that
detects the status of a signal.
Capacitor
Electrical
component
accumulating energy.
Oscillator
A device that moves back and
forth between two boundaries.
Cathode
The negative terminal of a
diode or other polarized
component.
PC Board
Printed Circuit Board.
Power Supply
An electronic circuit that
produces the necessary power
for another circuit or device.
CMOS
(Complimentary Metal Oxide
Semiconductor) A type of
transistor circuit which uses Pand N-type field-effect transistors.
Pulse
A sudden change from one
level to another, followed after
a time by a sudden change
back to the original level.
Current
The flow of electrons.
Resistor
Diode
An electronic component that
changes alternating current to
direct current.
An electronic component that
obstructs (resists) the flow of
electricity.
Speaker
Direct Current (DC)
Voltage that has polarity.
Frequency
The number of cycles per
second produced.
Component that converts
electrical energy into sound
energy.
Troubleshoot
To find and fix the problem with
something.
Impedance
Input Impedance
Integrated Circuit (IC)
Inverter
for
In circuit, the opposition that
circuit elements present to
alternating current.
The impedance seen by source
when a device or circuit is
connected across the source.
Any of a huge number of
semiconductor packages that
contain entire elements.
TTL (Transistor-Transistor Logic) A type of integrated circuit logic
that uses bipolar junction
transistors.
Voltage
The electromotive force that
“pushes” electrons through
conductive materials.
Zener
A type of diode that acts as a
voltage regulator by restricting
the flow of voltage above its
rating.
The circuit where the output state
is the opposite of the input state.
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SCHEMATIC DIAGRAM
REV-C
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